7.5HP Three Phase Motor Conversion

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Senior Member

Joined: 17/04/2008
Location: Canada
Posts: 196
Posted: 02:49pm 24 Sep 2008      

Thanks, I was hoping it would be of interest.

Dinges: ...and will be especially interested to see if the real results come close to your calculated values (using the mathematical model you have developed).

I'm keen to see if it works out, too. I've been bragging about my mathematical prowess for quite a while, now, but I have yet to produce hardware to bear out the theory. You'll be the first to know.

I didn't explain the FEMM very well. The rotor has 4 poles, and the stock stator is wound that way. To keep the windings as they are, I am putting 4 poles on the rotor. Each pole has 6 magnets, arranged 2x3. That's why you see three magnets with field lines at the top of the FEMM solution that don't connect. They are of the same pole, and the lines collect and travel together through the outer stator to the next pole, 90 degrees away.

Struggling with these magnets for hours has made me believe that mounting the magnets, say, as a 12-pole rotor, would be much easier. Mutual repulsion as I push these down is stronger because I am trying to push a N magnet pole between two other N magnet poles.

Weighing the work (and potential danger to fingers) of wrestling these magents around against the time required to re-wind one of these things (to increase the pole count) and I'm starting to see another reason to like what Peter did with his 10HP.

Cranking a magnet down on a 6-32 threaded rod might work, but it may be too flexible. Thanks for the suggestion. I will try that. Probably didn't consider it before, because it would require two people to make it work. Convincing my wife to help hold on to things may be trickier than manipulating the magnets themselves!

Steven T. Fahey